bulma (file, components): fix color fo icons: icons have no color specified anymore for a while, and use the color of parent elements. As they are often used in a `<a>` element (to work without javascript), they are often using a link color. This commit change a few icons to use a dark color instead.

@media (min-width: 500px) {
    #main_area {
        background-image: var(--bg-img);
        background-repeat: no-repeat;
        background-size: cover;
    }
}